The incorporation of moist-soil management techniques has become an increasingly important component in the management of wintering areas for migrating waterfowl. In California, the availability of wetlands continues to decline, water is being spread thinner amongst an increasing urban population, new models suggest that the extent of wetlands necessary to sustain waterfowl populations could be 37-50% higher than previously predicted, and recent research suggests the Central Valley is producing less food than previously assumed. All of these factors highlight the need to maximize the benefits provided by wetlands to ensure that the energetic needs of wintering waterfowl are met. In Chapter 1 we addressed this issue by experimentally evaluating several moist-soil management strategies used by wetland managers in California.

Disking and summer irrigations have been identified as two of the most effective management practices for increasing moist-soil seed production. Our evaluation focused on the influence of irrigation schedules on moist-soil seed production and the costs associated with those irrigations. We examined the effects of timing and duration of summer irrigations on moist-soil seed production using large scale (1.5 acre) replicated plots. We contrasted two sets of treatments focusing on the duration (7, 14 and 28 days) and frequency (1, 2 or 3) of summer irrigations. Response variables included: 1) vegetative structure and species composition, 2) moist-soil seed production, 3) water management and mosquito abatement costs, and 4) the cost-effectiveness of these practices.

Our results illustrated; 1) the importance of an irrigation early in the growing season (approximately 6 weeks after drawdown) to aid in the control of undesirable vegetation, 2) plant height was driven primarily by duration of irrigation rather than frequency of irrigation when 35 days are provided between irrigations and plots have been irrigated 6 weeks after drawdown, 3) no more than 2 irrigations were needed to maximize seed yield of barnyard grass, 4) the capabilities of water delivery systems can significantly influence costs associated with mosquito abatement, and 5) the most cost-effective strategy for irrigating barnyard grass was 2 irrigations of 7 days. In Chapter 2 we evaluated rapid assessment techniques for estimating moist-soil seed yield. Previous studies that have evaluated predictive methods for estimating seed yield focused largely on inflorescence characteristics to predict the seed yield (of an inflorescence). This may be of limited value to wetland managers who are interested in estimating seed production at a unit wide scale. In this chapter we: 1) evaluate the ability of inflorescence characteristics to predict the seed yield of an inflorescence, 2) evaluate the ability of inflorescence characteristics and other easy-to-measure variables in their ability to predict the seed yield of a wetland impoundment, and 3) quantify time and cost estimates for each of the predictive techniques evaluated. We found that ocular predictors such as plant height, percent cover, and inflorescence density were better predictors of seed yield at an impoundment level than predictors of inflorescence seed yield.

Terms of Use

The supplemental file or files you are about to download were provided to ProQuest by the author as part of a dissertation or thesis.
The supplemental files are provided "AS IS" without warranty.
ProQuest is not responsible for the content, format or impact on the supplemental file(s) on our system.
in some cases, the file type may be unknown or may be a .exe file.
We recommend caution as you open such files.

Copyright of the original materials contained in the supplemental file is retained by the author and your access to the supplemental files is subject to the ProQuest Terms and Conditions of use.

Depending on the size of the file(s) you are downloading, the system may take some time to download them. Please be patient.